1. Geant4 examples Sébastien Incerti On behalf of the Geant4 collaboration with special thanks to Luciano Pandola, INFN

2. PART 1 Setting up your Geant4 environment

3. 3 Getting started (1/2) We assume you have downloaded the Geant4 files for Vmware (Player for Windows users, Fusion for Mac users), from the web site http://geant4.in2p3.frhttp://geant4.in2p3.fr Start the Vmware Player/Fusion software Open the Geant4 files Make sure to activate file exchange between Windows/Mac and the Vmware environment

4. 4 Getting started (2/2) Log in Username : local1 Password : local1 Environment variables for Geant4 and associated tools are automatically defined when you open your session, from the file /usr/local/env/Cshrc You can define Geant4 user environment variables in your /home/local1/.ucshrc file

5. 5 Environment variables (1/2) Already set when you when you log in Variables are defined using the command setenv VARIABLE value You can access the value of the variable using echo $VARIABLE For Geant4 system $G4INSTALL Directory where Geant4 is installed Value is $G4SYSTEM Operating system Value is Linux-g++ $G4WORKDIR Directory where executable code will be stored Value is

6. 6 Environment variables (2/2) For data libraries $G4LEVELGAMMADATA Directory with the database of nuclear levels Value is $G4RADIOACTIVEDATA Directory with the databse of radioactive decay Value is $G4LEDATA Directory with the databse of low energy EM Physics Value is $G4NEUTRONHPDATA Directory with the databse of low energy neutrons (thermal-20 MeV) Value is $G4ELASTICDATA Directory with the databse of hadronic elastic scattering Value is $G4ABLADATA Directory with the databse of hadronic ablation models Value is

7. 7 Geant4 examples A number of ready-to-use examples are available in Geant4 Located in $G4INSTALL/examples Three categories Novice : basic functionalities of Geant4 Extended : specific functionalities (specific Physics processes, biasing, magnetic fields…) Advanced : full simulation of realistic use cases (medical physics, space, calorimetry…)

8. PART 2 Running N03 without macros with macros

9. 9 Let’s try example N03 Copy N03 to your home : cd cp –R $G4INSTALL/examples/novice/N03. cd N03 Read at the README file : simulation of a simple sampling calorimeter… Compile & link the example gmake Warning : environment variables must always be set before compiling & running an executable file.

10. 10 Running without macros Once compiled and linked, you can run the executable using simply : $G4WORKDIR/bin/Linux-g++/exampleN03 Use your Tab key for faster recognition of existing directories You get the following screen output No argument after executable name

11. 11 ************************************************************* Geant4 version Name: geant4-09-01-patch-01 (25-January-2008) Copyright : Geant4 Collaboration Reference : NIM A 506 (2003), 250-303 WWW : http://cern.ch/geant4 ************************************************************* ***** Table : Nb of materials = 13 ***** [...] ------------------------------------------------------------ ---> The calorimeter is 10 layers of: [ 10mm of Lead + 5mm of liquidArgon ] ------------------------------------------------------------ [...] You have successfully registered the following graphics systems. Current available graphics systems are: ASCIITree (ATree) [...] Idle> ************************************************************* Geant4 version Name: geant4-09-01-patch-01 (25-January-2008) Copyright : Geant4 Collaboration Reference : NIM A 506 (2003), 250-303 WWW : http://cern.ch/geant4 ************************************************************* ***** Table : Nb of materials = 13 ***** [...] ------------------------------------------------------------ ---> The calorimeter is 10 layers of: [ 10mm of Lead + 5mm of liquidArgon ] ------------------------------------------------------------ [...] You have successfully registered the following graphics systems. Current available graphics systems are: ASCIITree (ATree) [...] Idle> Running without macros

12. 12 What happened ? 1.the run is initialized 1.definition of materials, 2.build of geometry 3.set physics processes 4.set production cuts 5.... 2.a macro file vis.mac is automatically read to register the visualization drivers (default OGLIX) and the set-up is shown on a graphic window (OpenGL) 3.you get the Idle> prompt where you can enter commands interactively e.g. change geometry, decide which particle to shoot, which energy, execute another macro, shoot a particle,.. Running without macros

13. 13  10 layers : 10 mm Lead + 5 mm Liquid Argon  no magnetic field The default geometry What you get with the VRMLFILE visualization driver

14. 14 Let’s try to shoot a particle: Idle> /run/beamOn 1 By default, a 50 MeV e - is shot impinging perpendicularly on the calorimeter phot: Total cross sections from Sandia parametrisation. Sampling according PhotoElectric model [...] ========= Table of registered couples ======================== Index : 1 used in the geometry : Yes recalculation needed : No Material : Lead cuts : gamma 1 mm e- 1 mm e+ 1 mm Energy thresholds : gamma 100.511 keV e- 1.37814 MeV e+ 1.28002 MeV Region(s) which use this couple : DefaultRegionForTheWorld phot: Total cross sections from Sandia parametrisation. Sampling according PhotoElectric model [...] ========= Table of registered couples ======================== Index : 1 used in the geometry : Yes recalculation needed : No Material : Lead cuts : gamma 1 mm e- 1 mm e+ 1 mm Energy thresholds : gamma 100.511 keV e- 1.37814 MeV e+ 1.28002 MeV Region(s) which use this couple : DefaultRegionForTheWorld Initialization of physics tables Calculation of energy cuts Running without macros

15. 15 Running without macros ---------------------------------------- ---> End of event: 0 Absorber: total energy: 44.555829 MeV total track length: 2.9979304 cm Gap: total energy: 809.13499 keV total track length: 3.6520688 mm Run terminated. Run Summary Number of events processed : 1 User=0.01s Real=0.35s Sys=0.09s --------------------End of Run------------------------------ mean Energy in Absorber : 44.555829 MeV +- 0.12511652 eV mean Energy in Gap : 809.13499 keV +- 0.005999626 eV mean trackLength in Absorber : 2.9979304 cm +- 2.0295141 Ang mean trackLength in Gap : 3.6520688 mm +- 0 fm ------------------------------------------------------------ ---------------------------------------- ---> End of event: 0 Absorber: total energy: 44.555829 MeV total track length: 2.9979304 cm Gap: total energy: 809.13499 keV total track length: 3.6520688 mm Run terminated. Run Summary Number of events processed : 1 User=0.01s Real=0.35s Sys=0.09s --------------------End of Run------------------------------ mean Energy in Absorber : 44.555829 MeV +- 0.12511652 eV mean Energy in Gap : 809.13499 keV +- 0.005999626 eV mean trackLength in Absorber : 2.9979304 cm +- 2.0295141 Ang mean trackLength in Gap : 3.6520688 mm +- 0 fm ------------------------------------------------------------ Event summary Run summary

16. 16 You also get a visualization of the event you have just shot (50 MeV e - ) primary e - gamma-rays Default color code: red = negative charge blue = positive charge green = neutral Running without macros What you get with the DAWNFILE visualization driver

17. 17 Geant4 macros are ASCII files containing a sequence of Geant4 commands: # /run/verbose 2 /event/verbose 0 /tracking/verbose 1 # /gun/particle mu+ /gun/energy 300 MeV /run/beamOn 3 $G4WORKDIR/bin/Linux-g++/exampleN03 run1.mac The argument following the executable name is taken as a macro name, e.g. run1.mac Shoot 3  + of energy 300 MeV Running with macros

18. 18 ---> End of event: 2 Absorber: total energy: 125.1375 MeV total track length: 10.637355 cm Gap: total energy: 9.5302526 MeV total track length: 5.3417345 cm Run terminated. Run Summary Number of events processed : 3 User=0.01s Real=3.78s Sys=0.06s --------------------End of Run------------------------------ mean Energy in Absorber : 133.48424 MeV +- 7.4232944 MeV mean Energy in Gap : 9.8882883 MeV +- 274.14222 keV mean trackLength in Absorber : 10.969526 cm +- 4.7680992 mm mean trackLength in Gap : 5.3210426 cm +- 640.82289 um ------------------------------------------------------------ ---> End of event: 2 Absorber: total energy: 125.1375 MeV total track length: 10.637355 cm Gap: total energy: 9.5302526 MeV total track length: 5.3417345 cm Run terminated. Run Summary Number of events processed : 3 User=0.01s Real=3.78s Sys=0.06s --------------------End of Run------------------------------ mean Energy in Absorber : 133.48424 MeV +- 7.4232944 MeV mean Energy in Gap : 9.8882883 MeV +- 274.14222 keV mean trackLength in Absorber : 10.969526 cm +- 4.7680992 mm mean trackLength in Gap : 5.3210426 cm +- 640.82289 um ------------------------------------------------------------ Summary of event #2 (the 3 rd one!) Summary of the full run Running with macros

19. 19 primary  + gamma-rays delta-ray Screenshot of the 3 events Running with macros What you get with the DAWNFILE visualization driver

20. 20 $G4WORKDIR/bin/Linux-g++/exampleN03 run1.mac Note that is equivalent to $G4WORKDIR/bin/Linux-g++/exampleN03 [...] Idle> /control/execute run1.mac $G4WORKDIR/bin/Linux-g++/exampleN03 [...] Idle> /control/execute run1.mac command to run an external macro (but in the second case you will get the Idle> prompt back) Running with macros

21. 21 $G4WORKDIR/bin/Linux-g++/exampleN03 Idle> /control/execute newgeom.mac Idle> /control/execute run1.mac $G4WORKDIR/bin/Linux-g++/exampleN03 Idle> /control/execute newgeom.mac Idle> /control/execute run1.mac /N03/det/setNbOfLayers 1 /N03/det/setAbsMat Water /N03/det/setAbsThick 40 cm /N03/det/setGapMat Air /N03/det/setGapThick 0 cm /N03/det/setSizeYZ 40 cm /N03/det/setField 3 tesla /N03/det/update 1) First macro changes geometry: only one layer of absorber (40 cm of water), no gap (thickness = 0 cm)  practically a solid block of water Change transverse dimensions, set a 3 T magnetic field 2) Second macro shoots the 3 300-MeV  +, as before Change geometry on-the-fly

22. 22 primary  +  B B  B B Geometry, materials, magnetic field and primary particles can be tuned by ASCII macros, without recompiling the code ! x y What you get with the DAWNFILE visualization driver Change geometry on-the-fly

23. 23 Summary Geant4 provides several examples to show basic and advanced functionalities (novice/extended) and full- scale realistic applications (advanced). Environmental variables should be properly set to compile and run Geant4 applications. Geant4 applications can be run interactively (namely, giving commands by keyboard) or by macros. A few macros are distributed with the examples. Simulation parameters (geometry, visualization, primary particles, materials) can be tuned without recompiling the code.